Chaindrive

I checked my clearances for the first time last weekend while doing the 450 cam swap. They were TIGHT! At the very minimum side of the clearance range on all valves. It doesn't have a lot of miles/hours on it, but it is a '99. Wear should only increase clearances, so the Mobil 1 must be working.

EricZ

Be very careful Chaindrive. Tight clearances may be indicating a problem. As an engine wears, the valve clearances don't neccesarily increase, often times they decrease. This is caused by errosion of the valve seats in the heads and the subsequent "rising" of the entire valve over time. Keep an eye on those clearances so that you don't burn a valve.

Chaindrive

Eric &tc;
Thanks for the warning! I feel dumb for not considering the possibility of seat wear tightening things up! I guess I was only considering cam lobe, lifter, and stem wear. I would feel better with values in the middle of the tolerance range. Dang, I just ordered the new shims and will have to wait a week for them! Guess I better buy an assortment... And the weather is sooooo nice right now....

EricZ

No problem. I have the same problem with my 97 YZF 1000. ONE valve out of sixteen is too tight!! That means hours of labor to remove the bodywork, gas tank, airbox, carbs, cam cover and 2 camshafts to loosen one lousy valve. Plus it just wouldn't be any fun if I didn't drop SOMETHING into the engine.
Now that I think of it does anyone want to buy a slightly used YZF 1000. Needs minor work. LOL I need to buy a KTM Duke or something.